---
title: Reading agent state
icon: "lucide/ArrowLeft"
description: Read the realtime agent state in your native application.
---
import { ImageZoom } from 'fumadocs-ui/components/image-zoom';
import RunAndConnect from "@/snippets/integrations/langgraph/run-and-connect.mdx"
import { IframeSwitcher } from "@/components/content"

<IframeSwitcher
  id="shared-state-example"
  exampleUrl="https://feature-viewer.copilotkit.ai/langgraph/feature/shared_state?sidebar=false&chatDefaultOpen=false"
  codeUrl="https://feature-viewer.copilotkit.ai/langgraph/feature/shared_state?view=code&sidebar=false&codeLayout=tabs"
  exampleLabel="Demo"
  codeLabel="Code"
  height="700px"
/>

<Callout type="info">
  This example demonstrates reading from shared state in the [CopilotKit Feature Viewer](https://feature-viewer.copilotkit.ai/langgraph/feature/shared_state).
</Callout>

## What is this?

You can easily use the realtime agent state not only in the chat UI, but also in the native application UX.

## When should I use this?

You can use this when you want to provide the user with feedback about your agent's state. As your agent's
state updates, you can reflect these updates natively in your application.

## Implementation

<Steps>
  <Step>
    ### Run and connect your agent
    <RunAndConnect components={props.components} />
  </Step>
  <Step>
    ### Define the Agent State
    LangGraph is stateful. As you transition between nodes, that state is updated and passed to the next node. For this example,
    let's assume that our agent state looks something like this.

    <Tabs groupId="language_langgraph_agent" items={["Python", "TypeScript"]} persist>
      <Tab value="Python">
        ```python title="agent.py"
        from copilotkit import CopilotKitState
        from typing import Literal

        class AgentState(CopilotKitState):
            language: Literal["english", "spanish"] = "english"

        def chat_node(state: AgentState, config: RunnableConfig):
          # If language is not defined, set a value.
          # this is because a default value in a state class is not read on runtime
          language = state.get("language", "english")

          # ... add the rest of the node implementation and use the language variable

          return {
            # ... add the rest of state to return
            # return the language to make it available for the next nodes & frontend to read
            "language": language
          }
        ```
      </Tab>
      <Tab value="TypeScript">
        ```ts title="agent-js/src/agent.ts"
        import { Annotation } from "@langchain/langgraph";
        import { CopilotKitStateAnnotation } from "@copilotkit/sdk-js/langgraph";

        export const AgentStateAnnotation = Annotation.Root({
            language: Annotation<"english" | "spanish">,
            ...CopilotKitStateAnnotation.spec,
        });
        export type AgentState = typeof AgentStateAnnotation.State;

        async function chat_node(state: AgentState, config: RunnableConfig) {
          // If language is not defined, use a default value.
          const language = state.language ?? 'english'

          // ... add the rest of the node implementation and use the language variable

          return {
            // ... add the rest of state to return
            // return the language to make it available for the next nodes & frontend to read
            language
          }
        }
        ```
      </Tab>
    </Tabs>
  </Step>
  <Step>
    ### Use the `useCoAgent` Hook
    With your agent connected and running all that is left is to call the [useCoAgent](/reference/hooks/useCoAgent) hook, pass the agent's name, and
    optionally provide an initial state.

    ```tsx title="ui/app/page.tsx"
    import { useCoAgent } from "@copilotkit/react-core"; // [!code highlight]

    // Define the agent state type, should match the actual state of your agent
    type AgentState = {
      language: "english" | "spanish";
    }

    function YourMainContent() {
      // [!code highlight:4]
      const { state } = useCoAgent<AgentState>({
        name: "sample_agent",
        initialState: { language: "english" }  // optionally provide an initial state
      });

      // ...

      return (
        // style excluded for brevity
        <div>
          <h1>Your main content</h1>
          {/* [!code highlight:1] */}
          <p>Language: {state.language}</p>
        </div>
      );
    }
    ```
    <Callout type="info">
      The `state` in `useCoAgent` is reactive and will automatically update when the agent's state changes.
    </Callout>
  </Step>
  <Step>
    ### Give it a try!
    As the agent state updates, your `state` variable will automatically update with it! In this case, you'll see the
    language set to "english" as that's the initial state we set.

    <Frame>
      <ImageZoom src="https://cdn.copilotkit.ai/docs/copilotkit/images/coagents/read-agent-state.png" alt="read agent state" width={1000} height={1000} className="my-0"/>
    </Frame>

    <Callout type="info">
      Pictured above is the [coagent starter](https://github.com/copilotkit/copilotkit/tree/main/examples/coagents-starter) with
      the [implementation](#implementation) section applied!
    </Callout>
  </Step>
</Steps>

## Rendering agent state in the chat

You can also render the agent's state in the chat UI. This is useful for informing the user about the agent's state in a
more in-context way. To do this, you can use the [useCoAgentStateRender](/reference/hooks/useCoAgentStateRender) hook.

```tsx title="ui/app/page.tsx"
import { useCoAgentStateRender } from "@copilotkit/react-core"; // [!code highlight]

// Define the agent state type, should match the actual state of your agent
type AgentState = {
  language: "english" | "spanish";
}

function YourMainContent() {
  // ...
  // [!code highlight:7]
  useCoAgentStateRender({
    name: "sample_agent",
    render: ({ state }) => {
      if (!state.language) return null;
      return <div>Language: {state.language}</div>;
    },
  });
  // ...
}
```

<Callout type="info">
  The `state` in `useCoAgentStateRender` is reactive and will automatically update when the agent's state changes.
</Callout>

## Intermediately Stream and Render Agent State
By default, the LangGraph agent state will only update *between* LangGraph node transitions --
which means state updates will be discontinuous and delayed.

You likely want to render the agent state as it updates **continuously.**

See **[emit intermediate state](/coagents/shared-state/predictive-state-updates).**
